Frame for a backpack



FIG. 1 is a view in perspective of a frame for a backpack showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a top view thereof.

The broken line illustration in the drawings is for the purpose of depicting unclaimed portions of the frame for a backpack. The broken lines and portions they depict form no part of the claimed design. 

CLAIM The ornamental design for a frame for a backpack, as shown and described. 